Cummins ISV 5.0 Turbo Diesel First Look

Titanic Torque

Back in August, Nissan announced the next generation Titan would offer a 5.0 liter turbo diesel V-8 carrying the legendary Cummins name. At the time, both Nissan and Cummins were tight lipped about specifics, other than displacement and around 300 hp and in the neighborhood of 550 lb-ft of torque. The commercial version of the same engine, ISV 5.0 was just unveiled and it will give us more clues as to what we can expect to see in Nissan's next big truck.

The first question is why a V-8 when big diesels are usually I-6s. Cummins designed an engine that can directly replace gasoline V-8 and V-10s engines. A V-8 is roughly the length of an inline four and a half cylinder engine, so a longer engine compartment isn't necessary. Also packaging of blot-on ancillaries, like alternators, power steering pumps etc. is also very similar to those gas engines. The extra torque and efficiency of the diesel makes it worth all the trouble.

The commercial version of the ISV 5.0 will deliver 560 lb-ft of torque and will be available in anywhere from 200 -- 275 hp versions depending on application. The version for the Titan is still slated for 300 hp. Cummins says it will offer "best in class" economy and emissions, but honestly we aren't entirely sure exactly what class that is.

The basic specs of this engine will be familiar to fans of high-performance gas V-8s. The 90-degree block is made from vermicular graphite iron, which offers a significant weight savings over traditional grey iron. The crankshaft is forged steel, which not only maximizes its strength-to-weight ratio, but allows the use of a slightly smaller crank. The pistons are aluminum and deeply bowled to help contain combustion in the early stages. The heads are aluminum and use four valves per cylinder, which are operated by dual overhead camshafts. Cummins says the DOHC set-up allowed for lower noise, higher engine speeds and optimal placement of injectors and glow plugs.

Speaking of glow plugs, the ISV 5.0 is using a ceramic glow plug. Cummins says this will be a lifetime part and offers the advantage of faster start times, as quick as 2 seconds from a cold start in -25 F conditions. The fuel is sprayed directly into the combustion chamber with piezo injectors, which operate far faster than standard fuel injectors and allow up to seven injection events per combustion cycle. This precise control of fueling allows for a reduction in combustion noise and a reduction in emissions. The common-rail direct injection system is fed by a cam driven high-pressure fuel pump and operates at an astronomical 2000 bar or roughly 29,000 psi. Think about that next time you stick your head under the hood next to a running engine.

On the intake side, a variable geometry turbo feeds the engine through a front-mounted air-to-air intercooler. When this engine appears in the Nissan Titan, it will employ a compound turbo setup, better for generating power across a wider RPM range. While a few manufacturers are now doing liquid cooled after-cooling, Cummins engineers insist it isn't worth the extra weight and complexity. It is using liquid-to-air cooling for the cooled-exhaust-gas-recirculation system however. Piping the exhaust gas back into the combustion chamber slows down the formation of NOx during the combustion process.

What NOx is created, is dealt with in the ISV 5.0's after-treatment system. Two cans, roughly the size of something wearing a Fiat badge contain the Diesel Particulate Filter, DPF and the Selective Catalytic Reduction Cat or SCR. The DPF captures particulate matter, which is burned off in regenerative cycles when pressure sensors on both ends of filter register a predetermined differential. The SCR uses DEF to break down NOx into nitrogen and oxygen. I was assured the system will be smaller on the Titan, as the duty cycle on the heavier commercial trucks is higher.

We still don't know everything about the upcoming engine for the Titan, but hopefully this cleared up a few things. We were able to see the engines running in a few different types of vehicles and they are noticeably quieter than traditional diesel engines.

Even without knowing all the specs it is a safe bet that Nissan is going to make a big splash with the next generation Titan.